The present invention relates to an electric utility cross arm; and, more particularly, to an insulated unit which is easily convertible from single phase to three phase delivery. Further, the present invention provides a cross arm of simple, two-section, reinforced construction.
Power transmission lines are supported above ground to ensure isolation between the lines and the environment. While the most common arrangement for supporting such lines comprises a plurality of glass electrical insulators mounted on wooden cross arms attached to vertical wooden poles, U.S. Pat. No. 4,682,747 teaches the use of a modular power transmission support structure. This structure comprises a generally triangular central portion and two horizontal arms extending laterally from the base of the central triangular portion. The structural members of these cross arms comprise an outer shell formed of a polyester resin material and a plurality of alternating layers of polyester resin material and synthetic fabric contained within the shell. The inner core of each structural member contains a longitudinally extending metal bar or cable surrounded by a mixture of polyester resin and particulate matter. The present invention is a further improvement on this polyester resin, metal core structure. The elimination of the metal core and the substitution of reinforcing ribs reduces the weight of the assembly significantly and allows for the entire assembly to be of molded construction.